If rebooting the workstation did not help, then my next suggestion is to get everybody out of Quik Check and all other Accpac Plus programs. Then look for a file 'EZSEMTAB' in the data directory and either rename it or delete it. When you next open Accpac or Quik Check for Windows, it will be recreated.

This EZSEMTAB file keeps track of which processes are locked, and if a computer has a 'hiccup', then this file may have been corrupted. If you are getting a Locking message when no-one else is in the data, then this would be the next step.

Error 533 is typically a failry generic message and could mean a number of different things. Usually it occurs when printing reports, but it could be due to incompatible Crystal files on that workstation, no batches to print, or some other possibilities (such as record locking). Also make sure that Opportunistic Locking is disabled on this computer.